As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB THROUGH FL 290 LEFT DUCT PRESSURE WAS 50 PSI AND RIGHT DUCT PRESSURE WAS 25 PSI. LEVEL AT FL 380, LT AT 37 PSI AND RT 25 PSI. ACFT GROUNDED. PERFORMED ENGINE BLEED AIR SYS HEALTH CHECK ON NR 2 ENGINE IAW TASK CARD NR NG-36WC-00001. FOUND PRECOOLER CONTROL VALVE TO BE BAD. REPLACED PRECOOLER CONTROL VALVE IAW AMM 36-12-02. ACCOMPLISHED BLEED AIR CROSSOVER TEST IAW AMM 36-11-00. OPS CHECKED GOOD. COMPLETED T/C NG-36WC-00001.